Extensible surface wave transmission line

ABSTRACT

THIS INVENTION RELATES TO A SURFACE WAVE TRANSMISSION SYSTEM, IN WHICH THE CLOSED END OF THE SURFACE WAVE LAUNCHER IS FORMED AS A COAXIAL LINE HAVING AN INNER CONDUCTOR THROUGH WHICH A SURFACE WAVE CONDUCTOR SI MOVABLE, AND AN OUTER CONDUCTOR CONDUCTIVELY SUPPORTED ON ONE END, AND DIELECTRICALLY SUPPORTED ON THE INNER CONDUCTOR ON THE OTHER END OF THE COAXIAL LIN, AND CAPACITIVELY COUPLED TO THE INNER CONDUCTOR AT AN INTERMEDIATE POINT OF COAXIAL LINE SO AS TO PERMIT TUNING FROM THE THE OUTSIDE.

T.HAFNER Feb. 23, 1971 EXTENSIBLE SURFACE WAVE TRANSMISSION Fled May 24.1968 3 SheQts-Sheet 1v R E R m OA TH N EE VR NO -m H T T. HAFNER3,566,317 i EXTENSIBLE SURFACE WAVE'A TRANSMISSION' LINEv s sheets-sheeta Feb. 23;V 1971 j Filed May- 24. 1968 INVENTOR THEODORE HAFNER mc@ voxwww Feb. 42:3; 1971 lFiled May 24,1968

HolZONTAL i SWIVEL T. HAFNr-:R 3,566,317

EXTENSIBLE SURFACE WAVE TRANSMISSION'LINE 3 Sheetssheet 5 FIG. u.'

yINVENTOR l THEODORE HAFNER' United States Patent O 3,566,317 EXTENSIBLESURFACE VIAVE TRANSMISSION LIN Theodore Hafner, 1501 Broadway, New York,N.Y. 10036 Filed May 24, 1968, Ser. No. 732,502 Int. Cl. H01p 3/12;H0141 1/28 U.S. Cl. 333-95 10 Claims ABSTRACT OF THE DISCLOSURE Thisinvention relates to an assembly of a surface wave transmission linewith a winding mechanism in which a surface wave transmission line,after passing the closed end of a surface wave launcher, is fed unto awinding mechanism to be wound on `and wound off with a radius as not toproduce a definite deformation of the line so that the line willstraighten itself out automatically after being unwound and passing thelauncher at its open end.

In a more specific embodiment, the invention consists of a ying bodycomprising an antenna structure, means for propelling said structure,means for controlling the position of said structure, a ground stationand a tethering line connecting said structure to said ground station,said ground station comprising means for transmitting to, and receivingsignals from said ying body; and said tethering line being in the formof a surface wave transmissing line of a predetermined frequency range,including a core of sufficient mechanical strength to serve as atethering line, a conducting layersurrounding said core and a dielectriccoating surrounding said foil of a thickness sufficient to maintainsurface waves of said frequency range along said line, means on saidground station to transmit said surface waves, and means on saidstructure to receive said surface waves, said transmitting meansincluding launching means, permitting slidable passage of said surfacewave transmission line from its open end to its closed end, and meansfor selectively winding on `and off said line when emerging from saidlaunching means at said ground station.

These and other objects of the invention vwill be more fully apparentfrom the drawings annexed herein, in which FIG. l represents anextensible transmission line attached between a flying antenna structureand a ground station.

FIG. 2 shows a flying antenna structure in side elevation.

FIG. 3 represents a cross section through an antenna struction.

FIG. 4 shows a tethering line in accordance with the invention.

FIG. 5 shows a modification of FIG. 4.

FIG. 6 illustrates the specific structure of the tethering line inoperation.

FIG. 7 shows a tethering connection between an airplane and a `flyingantenna structure.

FIG. 8 shows a specific flying antenna structure.

FIG. 9 shows one of the parts of FIG. 1, especially the balun in greaterdetails.

FIG. l0 represents a modilication of FIG. 9.

FIGS. 1l and 12 show in front and side elevations respectively, `aspecic Winding mechanism for a surface 3,566,317 Patented Feb. 23, 1971wave transmission line such as illustrated in FIGS. 1 to 10.

As apparent from FIG. l, a surface wave transmission line such asillustrated in greater details in FIG. 4 or 5 is shown at 1, emergingfrom a motor-operated drum 2 and passing over rollers 3 to a surfacewave launcher (or receiver) 4 which is shown in an exploded View.

In this view, a balun 5 or transducer is indicated attached at 1 and itis adjustably connected through a clamp 6 and adjustable brackets 7 to aground support at 8. The other end of balun 5 is attached by anotherclamp 9 to horn 10 from which the surface wave conductor emerges at 11to extend over the desired distance to a iiying antenna structure whichin this case may be part of a balloon, helicopter or airplane,schematically indicated at 12.

At the top end, the surface wave conductor 11 enters a receiving horn 13which, when assembled, forms, together with clamp 14, balun 15 and clamp16, a surface wave receiving structure which is substantially identicalwith the launching structure described above.

While both surface wave launching and receiving structures aresubstantially supported, riding only on the surface wave conductor 11,which passes through them, the bottom launcher is also held back by linkstructure 7, and the receiver at the top by one or more steel ropes 17,all

i ICC this, of course, without impeding the winding on and oif of line11 by motor-operated drum 2.

Balloon 12 may have printed thereon a cross-shaped antenna pattern,schematically indicated at 13 and connected by coaxial cable or anyother transmission line indicated at 19, to the top balun 15.

Similarly, at the other or bottom end of line 11, the bottom balun 5 isconnected through a coaxial cable 20 or any other transmission line, toa receiver or a transmitter, or a transmitter-receiver unit, indicatedat 21, in

case the antenna pattern 18 at the top is to serve as a receiver,transmitter antenna or as both, transmitter and receiver antennasrespectively.

If required, ground station 21 may be controlled by, or may be used tocontrol, other equipment over a ground antenna schematically indicatedat 22.

FIG. 2 illustrated a specific flying antenna structure in which thesurface wave transmission line 11 is terininated at the top, not in ahorn type surface wave receiver which has to be connected to a iiyingantenna, such as 18 in FIG. Tl, but line 11 is connected directly to aturnstile antenna structure which is attached to line 11 and/or anextension of line 11, and which is schematically shown at 23 (see alsothe cross-section shown in FIG. 3) which has been so designed that thesurface wave field of transmission line 11 is matched with the -wavefield of turnstile antenna 23.

In order predeterminedly to direct the generally omnidirectionalradiation pattern of such a turnstile antenna 23, the supporting stem 24of the turnstile antenna 23 supports on insulating stub 25 the metalscreen 26 which also forms the wings of the iiying antenna structure 23,which are movably hinged to each other at 27, thereby insuring a desireddirectivitjy of turnstile antenna 23.

Control of the movements of these wings 26, around their common axis 27,is effected by a motor 28 and by signals derived from the ground station21 over line 11 which, as indicated above, not only serves as amechanical tethering line but also as a high frequency transmission linefor surface waves which have a considerable bandwidth orchannel-carrying capacity.

In order to further, and predeterminedly, stabilize the flying antennastructure an adjustable horizontal ap is attached at 29 to the wings 26.Flap 29 is controlled by a motor 30 which is also controlled by signalsderived from transmission line 11.

Flap 29 and wings 26 and their controls, may be effectively realized inany desired manner and, if necessary, as in any airplane, be formed asparts only of Wing and flap surface which are made adjustable andthereby controllable, all this without departing from the scope of thisinvention.

FIG. 4 shows a specific surface wave conductor, consisting of a strandedsteel rope 31 of sufiicient mechanical strength to support the windvelocity and other stresses encountered in its operation as a tetheringline.

In order to act as a surface wave conductor, steel rope 31 is surroundedby a conducting layer 32 which may be either a copper foil, or the likehighly flexible conducting layer, or a sodium coating, and asschematically indicated in the drawing, separated if necessary from thesteel rope 31 by an adhesive layer 33 which may also be conductive toincrease the consistency of conduction, especially at the high frequencyunder consideration, characteristic of surface wave transmission.

Another layer or coating which may be insulating in character asindicated at 34, may serve to insulate the conducting layer or layers32, 33 from steel rope 31, thereby permitting additional direct oralternating currents to be fed through the cable to provide energy tomotors or other equipment on the flying antenna structure, and/or heatthe surface wave conductor sufficiently to prevent excessive ice orsleet formation which would impair operation, or at least increase theloss of surface wave propagation. The pure polyethylene, 3S, whichmaintains the surface wave, is protected by a black polyethylene skin36.

On top of conducting layer or layers 32, 33 is arranged an insulatingcoating 35 of low-loss plastic such as pure polyethylene or Teon toconcentrate the surface wave to a radial distance corresponding to thatof the surface wave field radius, or the radial dimensions of thelaunching and receiving structure, which are generally of the order ofone wavelength of the operating frequency range.

In case polyethylene is used for surface wave concentration, the purepolyethylene sheeting is covered with a thin skin of black polyethylenewhich assures weather resistivity without substantially increasingpropagation losses.

Conductive layer or layers 32, 33 may be replaced by a single copperfoil embedded or sandwiched in a plastic medium such as polyamid whichis highly ilexible, thereby supporting the conducting layer in thevarious winding operations imposed on the cable. If necessary, theplastic may also be provided on one or both sides of the sandwich withan adhesive to increase the overall stability and especially the flexingstrength of the structure.

In a modification of the surface wave conductor shown in FIG. 5, thesteel rope and its conductive coating is replaced by finely strandedsteel wire in which each strand is individually copper-coated or -platedin the form of a Teflon (trademark) coated Copperweld (trademark) orCopperply (trademark) wire 37 which, by the number of strands, can beadjusted to the desired high tensile strength and elasticity, say 4000lbs, breaking strength, without losing its elasticity and flexibility sothat it can be continuously wound on and off a relatively small drumwhich, for example, may have a diameter of l5" for an overall cablediameter of 1A, or generally with a ratio of cable diameter to drumdiameter of the order of at least 1:50.

FIG. 6 explains the function of a surface wave cable such as illustratedin FIGS. 4 and 5, in which cable 38 under control of a drum 39 operatedby motor 40 is arranged to travel in either directions 41, passing alaunching or receiving structure as schematically indicated at 42. Whileconductor 37 is wound on drum 39 it is elastically and not permanentlydeformed. As it is Wound off drum 39 and as it passes the launching orreceiving structure 42, cable 37, under control of its own elasticity,will automatically become straight, thereby transmitting the surfacewave with a minimum of loss.

As apparent yfrom FIG. 7 a flying antenna structure 43 such asillustrated in FIGS. 2 and 3, is tethered through a surface waveconductor 44 from an airplane schematically indicated at 45.

In addition to wing and flap controls effected through surface waveconductor 44 in the manner described with respect to FIGS. 2 and 3, theantenna structure 43 may be propulsed itself by a motor 46 fed throughline 44 (see two conductor arrangements 31, 32, FIG. 4) and driving apropeller 47, and also controlled by command signals derived fromairplane 45 through the tethering surface Wave conductor 44.

In an alternative arrangement, shown in FIG. 8, motor 46 may be formedas a generator 43 which is driven by propeller 49 under control of themotion asserted by line 50, and the current of generator 48 may be usedto energize the ap and wing control motors indicated at 51 and 52respectively.

FIG. 9 shows in side elevation and in cross-section one of the coaxialtransducers or baluns shown in the exploded views of FIG. 1.

As apparent from FIG. 9, the transducer consists essentially of threeportions: a central portion '53, a front portion 54, and a rear portionor filter portion 55, which are all screwed together' to form a solidunit and therefore, if

necessary, can lbe replaced by the same or other parts fitting differentfrequency range requirements.

Passing through portions 53-55 is a surface wave conductor consisting ofa stranded steel rope 56 surrounded by a thin dielectric layer 57, acopperfoil 58, preferably attached by an adhesive (not shown) to layer57, and surrounded by the field concentrating dielectric 59 proper,ywhich consists of pure polyethylene schematically indicated at 59which, if necessary, may be further protected by a thin `black outerpolyethylene layer 60.

If necessary, copperfoil 57 may also be attached by an adhesive to layer59. Layers 58, 59 may be replaced by a Teflon or equivalent coating toproduce minimum loss with maximum weather resistivity and optimumabrasive characteristics.

The elastic flexibility of rope 56 combined with layers 57 and 60 may besuch as to produce the desired alternative straightening out and curvingrequired in accordance with the invention, during the different windingand unwnding operations.

Portion has a Teflon cylindrical sleeve insert which operates as afilter and the entire part S4, of course, can be replaced in accordancewith the mechanical requirements of wear and tear, but also depending onthe particular operating spectrum required of the surface waveconductor.

Center portion 53 is attached to end portion 55 by screws 61 and isfurther attached by other screws 62 which also connect the outer orfilter portion 55 to center portion 54 to which at its other end thehorn 63 is connected. The inner conductor of the entire balun structureis connected at one end to 53 by a screw connection 64 and at the otherend is spaced from portion 54 by a dielectric window 66 of plexiglass orthe like. Portion 54 also supports at 67 the coaxial connection of thebalun to the outside and a diametrical position 68 an adjustment probefor correcting the operating frequency range or bandwidth `withincertain limits.

FIG. 10 shows balun continuously adjustable for a variable frequencyrange. In this case, the inner conductor `68, supporting a surface waveconductor 70 proper is provided with a very fine outer thread.Similarly, the outer conductor 71 of the balun is provided lwith a fineinner thread. These threads permit the end plates of the balun, namelythe conducting end plate 72 and the dielectric end plate 73, to beadjusted in directions indicated `by arrows 74 and thereby adjust tooperating frequency range of the balun in a predetermined manner.

FIGS. 11 and 12 show a launching or receiver unit 75 attached to a reel76 of otherwise well-known construction, which is arranged rotatable orswiveling around a vertical axis 77. Launching unit 75 itself isattached to drum 78 rotatable about a horizontal axis schematicallyindicated at 79. In that way, launcher unit 75 under control of the dragexerted by the surface wave conductor 80 emerging from launcher unit 75may assume any position Ibetween the horizontal position shown in FIG.l1 at 75 in full line, and the vertical position 75 shown in dottedline, thus reducing strain on the entire structure as well as itsindividual parts to a minimum.

FIG. 12 shows in somewhat greater detail how the launcher unit 75 isattached to the walls 78 which in turn must be rotatable about drum axis81 by means of a pair of brackets 83 connecting the outer -walls 78 ofdrum 76 over the balun 83 to the horn 84 of the launcher unit 75. Ataxis 79 brackets 82 are mounted rotatably so as to permit theself-adjustment of the position of launcher unit 75 in accordance withthe principles set forth above, to be affording electric connection ofthe surface wave conductor and continuous transmission of the surfacewave from launcher to receiver and conversely, during the winding andunwinding operations with a minimum of strain.

While the invention has been described and illustrated with certainarrangements of conductors, insulators, launchers, receivers, antennas,terminal and control equipment, it is not limited thereto but may beapplied in any appropriate form or manner whatsoever without departingfrom the scope of this invention.

What is claimed is:

1. In a surface wave transmission line assembly, a surface wavelauncher, a surface wave transmission line passing through saidlauncher, from its open to its closed end; the closed end being formedas a coaxial line having an inner conductor permitting said surface wavetransmission line to freely move through said inner conductor; and anouter conductor conductively supported on said inner conductor at oneend, and dielectrically supported on said inner conductor on the otherend of said coaxial line, and capacitively coupled to said innerconductor at an intermediate point of said coaxial line so as to permittuning from the outside, of the energy fed through said coaxial linefrom and to said surface wave transmission line, su'bstantially withoutbeing alfected by the movement of said surface wave transmission linethrough said inner conductor; means for selectively winding on and oisaid surface wave transmission line after having passed through saidlauncher at its closed end; said surface wave transmission line beingwound with such a radius as not to produce a definite deformation ofsaid line so that said line will straighten itself out automaticallyafter being unwound and passing through said launcher at its open end.

2. Assembly according to claim 1 wherein said surface wave transmissionline consists of a tiexible elastic steel rope surrounded by a copperfoil and a dielectric coating surrounding said copper foil.

3. Assembly according to claim 1 wherein said surface wave transmissionline consists of stranded copper coated steel wire, whereby thestranding occurs substantially on the surface of the rope, said ropebeing surrounded by dielectric coating.

4. Assembly according to claim 2 wherein said dielectric coatingconsists of Tellen.

5. Assembly according to claim 2 wherein there is provided an additionalinsulation between the copper foil and the steel rope.

6. Assembly according to claim 2 -wherein said launching means arearranged to swivel with respect to said winding means so as to permitsaid launching means to follow the movement of the line during windingand unwinding operations.

7. Assembly according to claim 2 wherein said Winding means are arrangedto swivel with respect to their support so as to permit said windingmeans to follow the movement of the line during winding and unwinding0perations.

8. Assembly according to claim 2 wherein said winding and launchingmeans are rigidly attached to each other to form a solid unit, said unitbeing arranged to swivel so as to permit it to follow the movement ofsaid line emerging from said launching means at its open end.

9. Assembly according to claim 2 `wherein said winding and launchingmeans are ilexibly coupled to each other SO as to permit said launchingmeans to follow the movement of said line during fwinding and unwindingoperations.

10. Assembly according to claim 2 wherein said launching means, at itsopen end, has a horn portion to which feet guiding means are attached bymeans of radial strings.

References Cited UNITED STATES PATENTS 2,685,068 7/1954 Goubau 333-95SUX2,995,740 8/ 1961 Shreckengost 343-705X 3,077,569 2/'1963 Ikrath333--95SUX 3,134,951 5/1964 Huber 333-95SUX 3,241,145 3/1966 Petrides343-705 HERMAN K. SAALBACH, Primary Examiner T. VEZEAU, AssistantExaminer U.S. Cl. X.R.

